Over the past several decades, numerous efficient technologies have been developed to control or measure the flow of fluids. Designs of numerous flow control devices and valves are indebted to the development and advancement of oil, gas, and petrochemical industries in the past century. Design of many aerospace, chemical and mechanical systems have been dependent on assessment of amount of fluid passed a certain point in the process or in the equipment.
However, the available methods or equipment are most efficient in the conventional ranges used in the established industry. In microfluidic devices as used in emerging technologies, the features and passages of flow are extremely tiny in micron's range, and extra forces come to play and appear in the governing laws of fluid flow in the liquid or gas. These differences have created the necessity of new designs for specialized flow control.
For example, since recently, the procedure of assay to measure a property or concentration of an analyte is performed by efficient electro-mechanical microfluidic devices. Numerous types of assays include antigen capture assay, bioassay, competitive protein binding assay, crude oil assay, four-point assay, immunoassay, microbiological assay, stem cell assay, and numerous types of concentration assays.
There are several occasions in the process of an assay, for example, in which the flow of the liquid needs to be controlled by a valve. This situation is present in much other state-of-the-art equipment, such as lab-on-a-chip devices. Currently, we do not have a simple and efficient valve with extremely small leakage potential, and operable in the microfluidic systems, especially as used in MEMS and BioMEMS technologies.
In addition, microfluidics having crossing channels can bring various liquids for analysis in one area. However, the liquids must be passed in the right sequence, at the right time and using the right volume of solution. Typically, actuators or valves are used to stop or let a liquid pass in a microchannel. However, actuators are expensive to fabricate and necessitate peripheral equipment. Magnetically actuated valves are simpler to fabricate and actuate than many other types of valves.
The act of magnetic actuation can be done by as simply as applying an external magnetic field. However, because magnetic fields can have a long range effect on valves, external magnetic actuation of valves cannot work on specific magnetic valves that are closely spaced.